Sealing cap

ABSTRACT

The invention relates to a scaling cap ( 1 ) that is to be screwed and/or pressed onto the pouring neck ( 4 ) of a container, especially a bottle. Said sealing cap ( 1 ) comprises a particularly annular coaxial sealing lip ( 6 ) which is fixed within the bottom ( 2 ) of the cap and extends into the neck when the cap is mounted. The sealing lip is curved and/or buckled towards the outside between the upper and the lower end ( 7, 8 ) thereof in such a way that the curvature ( 12 ) and/or the buckled point ( 9 ) travel/s further out and the external face of the sealing lip sealingly rests against the interior wall of the neck when the sealing lip is compressed in an axial direction.

The invention relates to a cap closure for screwing or pressing onto apour neck of a container, in particular a bottle, comprising an inparticular annular coaxial seal lip that is attached to the end wall ofthe cap and extends into the neck when, the cap is mounted.

For the cap closure of a plastic bottle, it is also known from DE 42 03238 to mold onto the end wall of the cap an annular coaxial seal lip ofC-section such and convex outward. In this manner an additional sealingpoint with the inner wall of the bottle neck is provided on the outerface of the seal lip. Although the seal is improved as a result, thesealing pressure at this additional sealing point is limited.

The object of the present invention is to improve a cap closure of theabove-described type such that the additional annular seal lip achievesa high sealing pressure when the cap is mounted, in particular screwedon, so that the container withstands even high internal pressures.

This object is achieved according to the invention by the fact that theseal lip is outwardly curved and/or creased between the upper end andthe lower end thereof in such a way that the curvature and/or the creaseextends farther out and the outer face of the seal lip rests in asealing manner against the inner wall of the neck when the seal lip iscompressed axially.

Due to the compression of the seal lip axially, i.e. opposite thescrewing direction, such a design produces a high contact pressure ofthe outer face of the seal lip against the inner wall of the neck in aradial direction, resulting in an extremely tight seal. The design issimple and functions reliably even when the cap is screwed on and off anumber of times. In this manner the annular crease or annular outerregion of the curvature seals with the inner wall of the neck.

It is particularly advantageous when the pour neck on its inner wall hasat least one support surface against which the lower end of the seal lipabuts. In this manner the seal lip is reliably compressed, and the lowerend of the seal lip also forms an additional seal with the supportsurface. The support surface is preferably annular. The support surfacemay also be formed by at least two projections on the inner wall of thepour neck.

A further alternative proposes that the seal lip has at least twocreases. Improved movability of the seal lip at the attachment point tothe cap end wall is achieved when the upper attachment point has aweakened region, in particular a strip of reduced thickness of the seallip, between the seal lip and the cap end wall.

A precise, defined sealing surface, in particular a seal line, isachieved when the inner surface of the neck and/or the outer face of theseal lip have/has a raised location, in particular an annular bead,supporting the seal lip. The axial extension of the seal lip ispreferably 30-100% of the height of the cap. The spacing of the supportsurface from the upper end of the neck should be less than the axiallength of the seal lip.

Two illustrated embodiments of the invention are described below ingreater detail, and are illustrated in the drawing in axial sections, asfollows:

FIG. 1 shows a seal lip having an annular crease; and

FIG. 2 shows an outwardly curved seal lip.

A cap closure 1 manufactured by injection molding of plastic has anupper horizontal end wall 2 and a cylindrical side wall 3 that is moldedin a downward direction onto the outer edge of the end wall. Atamper-indicating ring may also be molded onto the lower end of the sidewall 3 so that it breaks off when the cap is opened. Such a cap 1 may bescrewed or pressed onto a cylindrical pour neck 4 of a container, inparticular a container neck such as for example a bottle. A screw thread5 is preferably provided between an inner face of the side wall 3 and anouter face of the neck 4.

An internal annular seal lip 6 is molded coaxial to the cap axis onto anunderside of the end wall 2, and extends downward and into the neck 4when the cap is set in place. The seal lip 6 flares radially outward sothat the outer circumference of the seal lip and therefore also thediameter is larger than the outer circumference and the diameter of theseal lip in the region of the attachment point 7 of the seal lip to theend wall 2 than at the lower free end 8. In the illustrated embodimentaccording to FIG. 1, this radially outward widening of the seal lip 6 isachieved by a crease 9, so that in the sectional view the wall of theseal lip resembles a toggle lever. In the illustrated embodimentaccording to FIG. 2 the seal lip 6 is outwardly curved, so that theouter face of the seal lip is convex and the inner face is concave.

A coaxial abutment ring 10 is molded onto the inner wall of the neck 4and projects inward to form an abutment surface 11 for the free lowerend 8 of the seal lip 6. Furthermore, the distance A from the stopsurface 11 to the upper end of the neck 4 is shorter than the length,i.e. the height, L of the seal lip 6, so that when the cap 1 isattached, in particular screwed, to the neck 4 the end 8 of the seal lip6 bears against the ring 10 and is thus compressed in such a way thatthe seal lip 6 is pressed outward, i.e. its diameter and circumferenceare increased at least in the center region. This compression of theseal lip 6 causes the curvature 12 and/or crease to project outward suchthat the seal lip is pressed against the inner wall of the neck 4 in asealing manner. At the same time, the inner face of the neck and/or theouter face of the seal lip may be formed with a raised annular region,in particular an annular bead, as a defined support and a secure seal.

In alternatives that are not illustrated, the seal lip may have morethan one, in particular two or three, creases. It may also beadvantageous for the upper joining point, i.e. the attachment point 7,to have a material weakening, in particular a reduction in thickness, ofthe seal lip to thus provide hinge action.

The abutment ring 10 and thus the stop surface 11 need not have acontinuous circumferential design, and the abutment ring 10 instead maybe composed of individual parts with gaps therebetween.

1. A cap closure (1) to be screwed and/or pressed onto the pour neck (4)of a container, in particular a bottle, comprising an in particularannular coaxial seal lip (6) that is attached to the end wall of the capand extends into the neck when the cap is mounted, characterized in thatthe seal lip (6) is outwardly curved and/or creased between the upperend (7) and the lower end (8) thereof in such a way that the curvature(12) and/or the crease (9) extends farther out and the outer face of theseal lip (6) rests in a sealing manner against the inner wall of theneck (4) when the seal lip is compressed axially.
 2. The cap closureaccording to claim 1, a characterized in that the annular crease (9) orannular outer region of the curvature (12) forms the seal with the innerwall of the neck (4).
 3. The cap closure and pour neck according toclaim 1, characterized in that the pour neck (4) on its inner wall hasat least one support surface (11) against which the lower end (8) of theseal lip (6) abuts.
 4. The cap closure and a pour neck according toclaim 3, characterized in that the support surface (11) is annular. 5.The cap closure according to claim 3, characterized in that the supportsurface (11) is formed by at least two projections on the inner wall ofthe pour neck (4).
 6. The cap closure according to claim 1,characterized in that the seal lip (6) has at least two creases.
 7. Thecap closure according to claim 1, characterized in that the upperattachment point (7) has a material weakness, in particular a reductionin thickness, of the seal lip between the seal lip (6) and the cap endwall (2).
 8. The cap closure according to claim 1, characterized in thatthe inner surface of the neck (4) and/or the outer face of the seal lip(6) have/has a raised location, in particular an annular bead, as asupport.
 9. The cap closure according to claim 1, characterized in thatthe axial dimension (2) of the seal lip (6) is 30-100% of the height (H)of the cap (4).
 10. The cap closure according to claim 3, characterizedin that a distance (A) from the support surface (11) to the upper end ofthe neck (4) is less than the axial length (L) of the seal lip (6). 11.In combination with a container pour neck centered on an axis, a capfittable axially over the neck and having an end wall and a side wall;an annular seal lip extending axially inward from an attachment point atthe end wall, fittable inside the pour neck, having an inner end, and ofa diameter that is greater at a central region between the attachmentpoint and the inner end than at the inner end; and a formationengageable with the inner end of the seal lip when the cap is fittedover the pour neck to axially compress the seal lip and force thecentral region radially outward into sealing engagement with an innersurface of the pour neck.
 12. The combination defined in claim 11,further a comprising screw formations between an outer surface of thepour neck and an inner surface of the side wall.
 13. The combinationdefined in claim 11 wherein the central region is in unstressedcondition of a diameter slightly smaller than an inside diameter of thepour neck.
 14. The combination defined in claim 11 wherein the lip iscreased and is formed by an outer frustoconical portion and an innerfrustoconical portion.
 15. The combination defined in claim 14 whereinthe creased lip is pressed substantially in line contact at its creaseagainst the pour-neck inner surface when compressed axially.
 16. Thecombination defined in claim 11 wherein the lip is of radially inwardlyconcave C-section.
 17. The combination defined in claim 11 wherein theformation is an annular shoulder formed in the pour cap and axiallyengageable with the end of the lip.
 18. The combination defined in claim17 wherein an axial distance between the shoulder and an outer edge ofthe pour neck is slightly shorter than an axial length of the lipbetween the end wall and its outer end.